Apparatus for and method of returning purged inert gas to an absorption refrigerating system



APPARATUS FOR AND METHOD OF RETURNING PURGED INERT Aug.30,1949. P, WHITLOW 2,480,530

.GAS TO AN ABSORPTION REFRIGERATING SYSTEM Filed Jan. 15, 1948 v INVA'NTOR. BY WJ w arraew-y Patented Aug. 30, 1949 2,4&0,530

APPARATUS FOR AND METHOD OF RETURN- ING PURGED INERT GAS TO AN ABSORP- TION REFRIGERATING SYSTEM Eugene P. Whit-low, Evansville, Ind., assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application January 13, 1948, Serial No. 2,096

9 Claims.

1 This invention relates to refrigeration and particularly to means for reducing superheat of a refrigerant-absorbent solution in the generator of a two-pressure absorption refrigerating system.

In absorption refrigerating systems of the twopressure type, particularly such systems which operateat low pressures, it has been found that an excess of non-condensable gasesoften collects in certain parts of such systems whereby the emciency of the system is reduced. It has also been found in practice that if a small amount of noncondensable gas is retained and circulated through a refrigerating system of the above type the system will operate more quietly, in that the circulated non-condensable gas forms vapor nuclei in the generator or vapor expeller of such system, whereby the refrigerant-absorbent solution boils more readily and superheat and its ensuing noise is reduced.

It is therefore an object of my invention to provide an improved method of, and apparatus for, continuously withdrawing any excess of noncondensable gases that accumulate in a refrigerating system of the above type, and during operation of such system to intermittently return a small but definite quantity of such withdrawn non-condensable gases to certain parts of; the refrigerating system.

The invention together with its objects and ad- 1 vantages wil be more clearly understood from the following detailed description taken in connection with the accompanying drawing, in which the single figure is a view diagrammatically illustrating a refrigerating system incorporating my invention.

For purposes of illustration, I have incorporated my invention in a two-pressure absorption refrigerating system like that disclosed in United States Patent to A. R. Thomas No. 2,384,860

be made thereto for a detailed description of the I refrigerating system. 7

As shown, the generator Ill includes an outer shell l5 within which are disposed a plurality of vertical riser tubes l6 having the lower ends thereof connected to receive liquid from an inlet chamber l1 and the upper ends extending into and above the bottom of a vapor separating vessel l8. A space l9 within shell l5 forms a chamber to which steam is supplied through a conduit 20 from a suitable source of supply, so that full length heating of the tubes [6 is effected. A vent 2| is provided at the upper end of shell I5, and a conduit 22 is connected to the bottom part of the shell for draining condensate from the space l9.

The system operates at a partial vacuum and contains, for example, a saline refrigerantabsorbent solution, in which water is the refrigerant and lithium chloride, lithium bromide or a mixture of the two is the absorbent. When steam is supplied through conduit 20 to space l9, heat is supplied to tubes l6 for expelling refrigerant vapor from solution. The residue absorption liquid is raised through tubes l6 by gas or vapor-lift action. The refrigerant vapor discharged from the upper ends of the tubes or risers l6 separates from the raised absorption liquid in the vessel l8 and flows through a conduit 23 into condenser I I wherein the vapor is condensed. The liquid refrigerant formed in the condenser flows through a U-tube 24 into a flash chamber 25 and from the latter through a tube 26 into evaporator I2.

The evaporator includes a plurality of horizontal banks of tubes 21 disposed one above the other and having heat transfer fins 28 secured thereto to provide a relatively large heat transfer surface. The liquid refrigerant flowing to the evaporator is divided in any suitable manner for flow through the uppermost bank of tubes 21. For example, the dividing of liquid may be effected by a liquid distributing trough 29 into which the liquid flows from the tube 26. The liquid refrigerant flows in successively lower tubes through suitable end connections which are open to permit escape of vapor from the tubes.

The liquid refrigerant supplied to tubes 2! evaporates therein to produce a refrigerating or cooling effect with consequent absorption of heat from the surroundings, as from a stream of air flowing over the exterior surfaces of the tubes 21 and fins 28. The vapor formed in tubes 21 passes out into end headers 30 which are connected at their lower ends to absorber l3. Any vapor formed in flash chamber 25 passes through a conduit 3| into one of the headers 30 and mixes with vapor formed in the evaporator l2, so that disturbances in the evaporator due to vapor flashing of incoming liquid are avoided.

In absorber l3 refrigerant vapor is absorbed into absorption liquid entering through a conduit 32. The entering absorption liquid flows into a vessel 33 in which liquid is distributed laterally with respect to a plurality of vertically disposed pipe banks 34 arranged alongside of each other. The liquid flows from vessel 53 through conduits 35 into a plurality of liquid holders and distributors 36 which extend lengthwise or and above the uppermost branches of the pipe banks 34. Absorption liquid is=si=phoned over the walls of the liquid holders 36 onto the uppermost pipe sections. Absorption liquid drips or trickles from each horizontal pipe section onto the next lower pipe section, sotha't all of the pipe sections are wetted with a film of absorption liquid. Absorption liquid enriched in refrigerant flows from absorber I 3 through a conduit 31, an inner group of passages in a liquid heat exchanger 38, a conduit 39, a stabilizing or leveling vessel 40, and a conduit 4| into the inlet chamber T7 or the generator. Refrigerant vapor is expelled from solution in the generator by heating, and the residue absorption liquid is raised by gas or vapor-lift action in riser tubes '16, as explained above.

The absorption liquid in vessel 48, rromwnroh refrigerant has been expelled, flows through a conduit #2, an outer roup of passages in liquid heat exchanger 3 8, and conduit "32 into the upper part of absorber l3. This circulation of absorption liquid is effected by raising liquid in the vertical riser tubes 1'6 by vapor-lift action, so that liquid can flow from the generator to the absorber and return [from the -'l'a'tter to the generator by force of gravity.

The upper part of vesselflu is connected by a conduit 43 to vessel 18, so that the pressure in vessel 40 is equalized with the pressure in the upper part of the generator and in the condenser. Vessel 48 is of 'sufficient volume to hold the liquid differential in the systemand is of sufficien't crosssectional area "that the liquid level therein does not vary appreciably, so that 'asubstantially constant reaction head is provided "for lifting "liquid intheriser tubes of the generator.

The heat liberated with absorption of water vapor in absorber 13 is transferred to :a cooling medium, such as water, which flows upward through the vertically disposed pipe banks 34. The cooling water enters the "lower 'end of the pipe banks through a conduit 64 and leaves the upper end of the pipe banks through a conduit '45. Conduit 45 is 'connec'te'd'to the condenser, so that the same cooling water "is utilized to effect coolingo'f both condenser H and absorber .153. From the condenser the cooling water flows through a conduit '46 to waste, or *to a cooling tower, not shown.

During operation of the refrigeration system, non-condensable gases may collect in both the high and lowpressure sides of the system. The non-'condens'able gases collecting in the highpressure side of the system, thatthe generator f and condenser 11, are carried to the dead or far endo'f the condenserin the bottom part thereof by the "sweeping effect or the refrigerant vapor flowing into the condenser. "Since the non-condensabl'e gases are swept to the bottom part .of

' ing through tribe 24tothe evaporator carries with it the non-condensable gases collecting in the condenser and generator.

The non-condensable gases in the low-pressure side of the system, that is, in the evaporator 12 and absorber l3, are carried to the bottom center part of the absorber by the sweeping action of the refrigerant vapor entering the top of the absorber through headers 30. In order to localize the non-condensable gases in a relatively small space, such gases are withdrawn from the bottom part of main absorber l3 through a conduit and-delivered to the top of an auxiliary absorber 5!. A small portion of the absorption liquid flowing toward the upper part of absorber i3 in conduit 32 is diverted into a conduit 52. A screen, not shown, removes any foreign matter the diverted liquid that would tend to clog a flow-restricting device 54, and the restricting device in turn limits the rate at which liquid is diverted into conduit 52 from the main stream of absorption Tiquid flowing i-n conduit 32. The "auxiliary absorber-is provided with plates, not shown, over which the diverted absorption liquid iiows.

While the gases withdrawn from absorber l3 through conduitbfl into auxiliary absorber 5i are for the most "part non co'nden'sable, these gases are not sufficiently' -local'i'zed in the bottom of the main absorber l3 and tests have shown that refrigerant vapor accompanies the non-condensaible gases withdrawn from the main absorber. For this reason the gases withdrawn from main absorber l 3 are brought into intimate contact with the diverted -a3bsorption liquid in auxiiiary absorber 51, whereby the refrigerant vapor accompanying the non-condensaible gases "is absorbed into the absorption liquid. The heat liberated with absorption of refrigerant vapor in the auxiliary absorber is transferred to a cooling medium fiow'ing through a coil 55 connec'ted'between'the inletoonduitld andoutlet conduit the cool in'gs'ystem'df the main absorber. The absorption liquid and gases both flow downwardly in intimate contact with each other in the auxiliary absorber and the gases arrive at the bottom part of the auxiliary absorber substantially stripped of refrigerant vapor.

The liquid flowing by gravitytothebottompart of the auxiliary absorber enters the upper end of a'conduit 56 until the conduit isclosed with liquid and sealed from the gases in the bottom .part of the auxiliary absorber. When the liquid level rises sufficientlyin the upper curved or bent portion of conduit 56, the small quantity of liquid within the open end is siphoned past the bend into the downwardly depending straight portion thereof. When liquid is siphoned from the upper curved-end of conduit 56, the liquid level falls in the bottom part of the auxiliary absorber below the upper open end o'f1conduit56, sothat noncondensable gases pass .into the upper bend ,or curved part of this conduit. The liquid levelin the bottom part of the absorber 5'! again rises to close and seal the upper end .of conduit 56, and, when the liquid level again rises sufiiciently, a small quantity of liquid is oncemoresiphoned into the downwardly depending portion of conduit 56. In this "way small quantities of non-,condensable 'ga'ses are withdrawn from the bottom part of auxiliary absorber 5! and trapped between successive slugs of liquid formed at the upper curved or bent portion of the conduit 56. Conduit .56, which may be referred to as a fall tube .pump, is of.such size that how of liquid is not appreciably restricted, howeverythe internal diameter is such that gas and liquid cannot pass each other while flowing downwardly through this conduit.

In accordance with my invention, a vessel 51 is connected to the lower part of vapor separating chamber l8 by a short conduit 58, which conduit is provided with a metering orifice 59. To prevent the metering orifice from being clogged by foreign matter, a screen 60 is located at the inlet of the conduit 58. A well 6| projects from the lower portion of vessel 51 and the top of vessel 51 is connected to an upper portion of the vapor separating chamber l8 by a vent conduit 62. An automatic siphon tube 63 connects the lower portion of well 6| to the leveling chamber 40. A conduit 54 extends upwardly from the lower portion of well BI and then downwardly to a gas trap 65, into which gas trap the purge pump 56 discharges absorption solution and non-condensable gases. A conduit 66 connects the gas trap 65 with a purge reservoir 61. pump 68 is connected to the purge reservoir by a conduit 69, which conduit is provided with a valve 10. A conduit 1| connects the lower portion of gas trap 65 to conduit 31, which latter conduit conveys absorption liquid from the main absorber l3 to the gas heat exchanger en route to the generator. Conduit 1| may, however, lead directly from gas trap 65 to the inlet chamber l1 of the generator.

In operation, when the unit is in operation and absorption liquid is lifted through the riser tubes I6 into the separating chamber l8, the major part of this liquid flows through conduit 42, liquid heat exchanger 38 and conduit 32 into the main absorber l3, as explained above. sorption solution also flows from chamber l8 through conduit 58 and metering orifice 59 into vessel 51. The solution level rises in vessel 51 until the level therein reaches the top of siphon tube 63, at which time the siphon starts and empties the vessel 51 and thewell 6| into leveling chamber 40. When the level of solution in the well reaches the lower end of the siphon tube, the column of liquid will break and the siphon will stop. Then vessel 51 will begin to fill up again and the cycle will be repeated. Concurrently with this operation, purge pump 56 will discharge absorption solution and non-condensable gas into gas trap 65. The gas will collect in the top of trap 65 and in conduit 64, and the 50 liquid will flow through conduit 1| and join the main stream of absorption liquid flowing through conduit 31 en route to the generator. If the solution level in the well 6! is low, the gas in the trap 65 and conduit 64 will escape into the vessel 51, from whence such gas flows through vent conduit 62 into separating vessel l8, and from there the gas flows through conduit 23 into the condenser II, From the condenser the non-condensable gas is carried through trap 41 and U- tube 24 into the evaporator I2, and. from the evaporator the non-condensable gases flow into the main absorber, as explained above.

The non-condensable gas returned to the main absorber I3 is brought into intimate contact with .65

absorption liquid which trickles downward over the pipe banks 34, whereby at least a portion of the non-condensable gas is absorbed or dissolved by the absorption liquid and carried therewith through conduit 31, inner passage of the liquid heat exchanger 38, conduit 38, leveling vessel 40 and conduit 4! into the inlet chamber I 1 of the generator. In the generator thenon-condensable gas forms vapor nuclei whereby the refrigerant-absorbent solution contairiedtherein boils- An evacuating 2O more readily and superheat and its ensuing noise is reduced. Any non-condensable gas that is returned to the main absorber l3 beyond that picked up by absorption solution therein and conveyed to the generator, as explained above,

is removed from the main absorber through conduit 50, auxiliary absorber 5| and purge pump 56 to the gas trap 65, as explained above. Solution flowing into vessel 51 continuously will raise the level in the well 6| rapidly and stop the flow of non-condensable gas from conduit 64 into vessel 51. In this manner gas will collect ingas trap 65 until the solution level therein is depressed to the point at which conduit 66 enters the gas trap, in which case excess gas will then flow through conduit 66 into purge receiver 61, from whence such excess gas may be exhausted from time to time by pump 68. In the meantime, vessel 51 will be filling with liquid. When vessel 51 is filled the automatic siphon will begin functioning and will again empty vessel 51 and well 6|. Then the non-condensable gas in trap 65 and conduit 64 will again be conveyed into vessel 51 and the cycle will begin again.

The metering orifice 59 intube 58 limits the rate at which absorption liquid flows into the vessel 51. The rate at which liquid flows into this vessel and the volume of the vessel, as well as the rate at which the automatic siphon 63 empties this vessel, determine the length of the cycle. These factors may be varied to yield the optimum results. The amount of non-condensable gas that is fed back to the system depends upon the filling-draining cycle for vessel 51 and on the volume of non-condensable gas held in gas trap 65 and in conduit 64. Both of these factors may be adjusted to give the most desirable results. Vessel 51 should be relatively small so thatv the alternate filling and dumping thereof will not cause too great a variation in liquid level in the leveling chamber 46. The height, 64*, to which conduit 64 rises must be great enough to prevent the siphoning of liquid from vessel 51 through conduit 64. As shown, one end of conduit 64 extends down into the well 6| a distance such that gas will not flow through this conduit when the well is full of liquid. Well BI is made small in diameter so that after the liquid has been siphoned therefrom, the level therein will rise rapidly to the point that conduit 54 will stop discharging non-condensable gas into vessel 51. The inlet end of siphon tube 63 need not extend to the bottom of well 6| but only to a depth such that when the liquid level is dropped to that point, the non-condensable gas in conduit 64 will discharge through the well and into vessel 51.

It is to be noted that, for purposes of illustration, the automatic siphon 63 is shown as discharging into leveling vessel 40. However, this siphon may discharge directly into the inlet chamber ll of the generator, or it may discharge into the bottom of the inner passage of heat exchanger 38. Also, by providing a liquid trap, not shown, in conduit 58 between vapor separating chamber l8 and vessel 51, conduit 52 may be connected directly to the main absorber l3 instead of to the vapor separating chamber l6, as shown, in which case non-condensable gas would flow from gas trap 65, through conduit 64, well 6!. vessel 58 andconduit 62 to the main absorber l3.

The arrangement and dimensions of flow restrictor 54, auxiliary absorber 5i, purge pump 56 and gas trap 65 are such that the purge pump may be said to deliver non-condensable gas and absorption liquid to the gas trap in a more or less continuous stream, Whereas, the arrangemerit and dimensions of conduit 58, metering orifice 59, vessel 51, well 6% and siphon 63 are such that there is a definite time interval be-, tween the filling and emptying of vessel 51- and; well 6|, so that a predetermined amount of noncondensable gas is accumulated and stored in the upper part of gas trap 55 and in conduit 641 between each fillin and emptying of; vessel 51 and well 6|, whereby a predetermined amount of non-condensable gas is delivered tothe vapor separator each time the well 6| is emptied.

The refrigeratin system illustrated and described herein is generally referred to as a cone tinuous-absorption refrigerating system of the two-pressure type, in that, so longas the medium which is being cooled demands refrigeration, the system operates continuously. HOW. ever, when the refrigeration demands on the sys tem are satisfied the system shuts down until such time as the demand for refrigeration is renewed. In other words, the system operates on on periods when there is a demand for nefrigeration, and on off periods when the demand for refrigeration is satisfied. Also, the particular refrigerating system illustrated and described herein may be said to have two main cir! cuits or paths of flow for working media, and three auxiliary or by-pass circuits for flow of working media. A first main circuit includes the generator Hi, vapor separator l8, conduit 23, con" denser H, U-tube 24, flash chamber 25, conduit 26, evaporator I2, absorber i3, conduit 31, the inner passage of liquid heat exchanger 38, con-,- duit 39, stabilizing vessel 49, and conduit 4| back to the generator Iii. A second main circuit includes the generator l0, vapor separator l8, conduit 42, the outer passage of liquid heat exchanger 38, conduit 32, absorber l3, conduit 37, the inner passage of gas heat exchanger 38, conduit 39, stabilizing vessel 46, and conduit 4| back to the generator ID. A first auxiliary circuit includes the generator l0, vapor separator 18, conduit 42, the outer passage of liquid heat exchanger 38, conduit 32, conduit 52, auxiliary absorber 5i, purge pump 55, gas trap 65, conduit H, conduit 31,, the inner passage of liquid heat exchanger 38, conduit 39, stabilizing vessel 46, and conduit 4! back to the generator. A second auxiliary circuit includes the main absorber l3, conduit 58, auxiliary absorber 5i, purge pump 56, gas trap 65, conduit 66, well 6|, vessel 51, conduit 62, vapor separator l8, conduit 23, condenser H, U-tube 24, flash chamber 25, conduit SI, and evaporator l2 back to the main absorber. A third auxiliary circuit includes the generator Ii], vapor separator l8, conduit 58, vessel 57, well 6 l siphon 63, stabilizing vessel ,3, and conduit 41 back to the generator.

Having thus disclosed my invention, I wish it understood that I do not desire to be limited to the particular structure illustrated and described, tor various modifications thereof may occur to a person skilled in the art.

What is claimed is:

1. An absorption refrigerating system having a high and a low-pressure side and including a generator, a condenser, an evaporator, an absorber and conduits interconnecting said elements providin main and auxiliary circuits for flow of working media therethrough, means for accumulating non-condensable gas in a main cir cuit for working media, means for withdrawing at least a portion of the accumulated non-con.- densable gas from said main circuit, means for storing the withdrawn non-condensable gas out li h main circuit, means providing a liquid Seal; for temporarily retaining the withdrawn non. condensable. gas in, storage, and means for intermittently fillin and drainin the liquid seal during continuous on periods of operation of the system, whereby non-.condensable gas is with-. drawn from a main circuit. for Work g media, temporarily stored out of the main circuit, and thenreturning to, the main circuit during on pe-v riodsof operation of the system.

2. An, absorption refrigerating system having a high and a low-pressure side and including a generator, a vapor separator, a condenser, an evaporator, an absorber: and conduits interconmeeting said elements providing main and auxiliary circuits, for flow of working media there through, meansv for. accumulating non-condensable gas in a. main Qircuit for working media, means: for withdrawing at leastv a portion of the accumulated non-condensable gas from said main circuit; a as. trapfor st rin a predetermin d amount of the withdrawn non-condensable gas out of the main circuit, a connection between said gas trapandsaid vapor separator for flow of ncn-condensable gas from the former to the latter. means in said connection providing a liquid seal for temporarily retaining'the withdrawn gas in storage, and means for intermittently filling and emptying the liquid seal during continuous onv periods of operation ot the system, whereby non-condensable gas; is withdrawn from a main circuit for Working media, temporarily stored out of said main circuit and then delivered to the vapor separator during 011, periods of operation of the system.

3. An absorption refrigerating system having a high and a low-pressure side and including a generator, a vapor separator, a condenser, an evaporator, an absorber and conduits; interconnecting said elements providing main and auxil' iary circuits for flow ofworking media there" through, means for accumulating non-condensable gas-in the absorber of said system, means for withdrawing at least a portion of the accumulated non-condensable gas from said absorber,'a gas trap for storing a predetermined amount of the withdrawn non-condensable gas, a connection between said gas trap and said vapor separator for flow of non-condensable gas from the former to the latter, means in said connection providing a liquid seal for temporarily retaining the withdrawn gas in storage, and means for intermittently filling and emptying the liquid seal during continuous operation of the system, whereby non-condensable gas is withdrawn from the, absorber, temporarily stored in the gas trap and then delivered to the vapor separator during n periods of operation of the system.

4; An absorption refrigerating system includin a high and alow-pressure side, means for collecting non-condensable gas in the low-pressure side of the system, means for entraining at least a pio i liqn. i the collected non-condensable gas into absorption solution in the low-pressure side oi the. system. m an f r withdrawing from the low-pressure, side of the System at least a portion of any remaining n n-c ndensable gas beyond that entrained in the. ab orp ion l t n, a a trap for. storing the withdrawn non-condensable gas, fitliuct llfe connecting said gas trap to the high-pressure, side. of system for flow of stored nonecondensable gas therethrough from the farmer to the latter, means in said structure twi ing a liquid. sea-l which blocks he fl w o non-condensable gas therethrough, and means for intermittently filling and emptying said liquid seal, whereby non-condensable gas is intermittently stored and returned to the high-pressure side of the system during on periods of operation thereof.

5. An absorption refrigerating system including a enerator, a vapor separator, a condenser, an evaporator, an absorber and conduits interconnecting said elements for flow of a refrigerating medium and an absorption solution, and means for retaining a predetermined amount of non-condensable gas in said system and for exhausting from the system any non-condensable gas beyond the predetermined amount retained therein, said last-named means including a gas trap, a fall tube connected between said absorber and a lower portion of said gas trap, a purge reservoir located above and connected to an intermediate portion of said gas trap, a connection between the top of said gas trap and said vapor separator providing a path of flow for non-condensable gas from the former to the latter and means in said connection for intermittently opening and closing said path of flow during continuous on periods of operation of the system, the construction and arrangement being such that non-condensable gas is withdrawn from the absorber of said system and delivered to said gas trap until a predetermined amount of gas is accumulated in said trap when the path of flow between the gas trap and the vapor separator is closed, thereafter, any non-condensable gas delivered to said trap beyond the predetermined amount stored therein is conveyed therefrom to said purge receiver, and during on periods of operation of said refrigerating system when the path of flow between the gas trap and the vapor separator is open the predetermined amount of non-condensable gas stored in said gas trap is delivered to the vapor separator.

6. In the art of refrigeration through the agency of a two-pressure absorption refrigerating system including a generator, a condenser, an evaporator, an absorber and conduits interconnecting said elements providing main and auxiliary circuits for flow of working media therethrough, that improvement which comprises withdrawing non-condensable gas from a main circuit of said system, storing at least a portion of the withdrawn non-condensable gas in an auxiliary circuit during operation of the refrigerating system, accumulating absorption solution in a path of flow of non-condensable gas between the main circuit and the auxiliary cirouit whereby the stored non-condensable gas is temporarily held in storage, and removing the accumulated absorption solution from the path of flow of non-condensable gas between the main and auxiliary circuits during on periods of operation of the refrigerating system, whereby the stored non-condensable gas is returned to the main circuit during on periods of operation.

7. In the art of reirigeration through the agency of a two-pressure absorption refrigerating system including a generator, a vapor separator, a condenser, an evaporator, an absorber and conduits interconnecting said elements providing main and auxiliary paths for flow of working media therethrough, that improvement which comprises withdrawing noncondensable gas from the absorber of said system, storing the withdrawn non-condensable gas in an auxiliary path of flow between the absorber 10 and vapor separator during on periods of operation of the refrigerating system, accumulating absorption solution in said auxiliary path of flow, whereby the stored non-condensable gas is temporarily held in storage, and removing the accumulated absorption solution from the auxiliary path of flow during on periods of operation of the system, whereby the stored non-condensable gas is delivered to the vapor separator during on periods of operation.

8. In the art of refrigeration through the agency of an absorption refrigerating system of the two-pressure type, which system includes a generator, a vapor expeller, a condenser, an

evaporator, an absorber and conduits interconnecting said elements for flow of a refrigerating medium and an absorption solution, that improvement which comprises accumulating noncondensable gas in the absorber of said system, subjecting the accumulated non-condensable gas to absorption solution whereby at least a portion of the accumulated non-condensable gas is entrained by the absorption solution, flowing the absorption solution and entrained non-condensable gas to the generator of the system wherein the entrained gas forms vapor nuclei which promote quiet boiling of the absorption solution, withdrawing from the absorber at least a portion of any excess of accumulated non-condensable gas beyond that entrained by the absorption solution, temporarily storing the withdrawn noncondensable gas during on periods of operation of the system, anddelivering the stored noncondensable gas to the vapor separator during said on periods of operation.

9. In the art of refrigeration through the agency of an absorption refrigerating system of the two-pressure type, which system includes a generator, a condenser, an evaporator, an absorber and conduits interconnecting said elements for flow of a refrigerating medium and an absorption solution, that improvement which comprises accumulating non-condensable gas in the absorber of said system, subjecting the accumulated non-condensable gas to absorption solution whereby at least a portion of the accumulated non-condensable gas is entrained by the absorption solution, flowing the absorption solution and entrained non-condensable gas to the generator of the system wherein the entrained gas forms vapor nuclei which promote quiet boiling of the absorption solution, withdrawing from the absorber at least a portion of any excess of accumulated non-condensable gas beyond that entrained by the absorption solution, storing at least a portion of the withdrawn non-condensable gas during on periods of operation of the system, deliverin the stored noncondensable gas to the vapor separator during said on periods of operation, and exhausting from the system any excess of withdrawn noncondensable gas beyond the amount stored and delivered to the vapor separator, whereby a given amount of non-condensable gas is retained and circulated through the system.

EUGENE P. WI-IITLOW.

REFERENCES CITED UNITED STATES PATENTS Number Name Date A. R. Thomas Sept. 18, 1945 

